Lubrication system for an attritable engine

ABSTRACT

A gas turbine engine with a lubrication system includes a ball bearing assembly and a rotor circumscribing a rotational axis and journaled within the ball bearing assembly. The gas turbine engine also includes a lubrication system located radially outward from a rotational axis and radially outward and adjacent to the ball bearing assembly, which includes a lubrication channel having an inlet and an outlet and a dispersion cone adjacent to the outlet of the lubrication channel.

This application is a continuation of U.S. patent application Ser. No.16/736,385 filed Jan. 7, 2020, which is hereby incorporated herein byreference in its entirety.

BACKGROUND

The present disclosure relates generally to attritable aircraft engines.More specifically, this disclosure relates to a lubrication network ofan attritable aircraft engine.

Attritable aircraft can include, for example, Unpiloted (or Unmanned)Aerial Vehicles (UAVs) and expendable turbojet systems for guidedmunitions, missiles, and decoys. Attritable aircraft are generallydesigned as limited lifetime vehicles, with expected lifetimes as shortas a single use or single mission vehicle. As such, many components andfeatures common in traditional piloted aircraft are unnecessary or canbe simplified for attritable aircraft applications, including fluiddispensing systems.

Fluid dispensing system in aircraft systems can have five or moreindividual parts, each requiring assembly, which can be expensive andtime consuming. Furthermore, cross drilling through the engine supportstructures has conventionally been used in order to create necessaryfluid passageways, which adds additional labor and expense to themanufacturing process.

Proper lubrication is essential for a variety of engine components,including ball bearing assemblies. Improper lubrication can lead toover-heating of system critical parts, which can cause catastrophicfailure. On the one hand, enough lubrication fluid must be provided toensure sufficient cooling of the bearings under all working conditionsof the gas turbine engine. On the other hand, excessive lubricationfluid may require larger fluid pumps and piping systems than necessary,increasing the footprint of the lubrication system and the overall costand weight of the aircraft engine. Furthermore, pumping unnecessarylubrication fluid through an engine system uses energy that could beused elsewhere in the system. As such, providing too much lubricationfluid results in a less efficient gas turbine engine compared to a gasturbine engine provided with a proper amount of lubrication fluid.

SUMMARY

A gas turbine engine with a lubrication system includes a ball bearingassembly and a rotor circumscribing a rotational axis and journaledwithin the ball bearing assembly. The gas turbine engine also includes alubrication system located radially outward from a rotational axis andradially outward and adjacent to the ball bearing assembly, whichincludes a lubrication channel having an inlet and an outlet and adispersion cone adjacent to the outlet of the lubrication channel.

A method of manufacturing a gas turbine engine with a lubrication systemincludes journaling a rotor within a ball bearing assembly andcircumscribing a rotational axis. The method also includes additivelymanufacturing a lubrication system located radially outward from arotational axis and radially outward and adjacent to the ball bearingassembly, which has a lubrication channel with an inlet and an outletand a dispersion cone adjacent to the outlet of the lubrication channel.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of an attritable engine with alubrication system.

FIG. 2 is a cross-sectional view of a spray cone with an airfoildistribution array.

DETAILED DESCRIPTION

An attritable engine with an integrally built fluid dispensing systemsimplifies manufacturing. An attritable engine can leverage additivemanufacturing techniques to improve various aspects of the limited-lifeengine. For example, additive manufacturing allows assembly details tobe unitized, and simultaneously permits integration of many complexperformance-enhancing features. The additive manufacture of the enginereduces the time to delivery to the customer and lowers the overallproduction costs of the unit.

Disclosed herein is a lubrication system having a dispersion coneconfigured to form a mist of lubricant, which evenly covers the exteriorsurface of the outer races. The evenly distributed lubricant cools ballbearing assemblies during operation of the engine. Furthermore, thelubrication system can be additively manufactured, obviating the needfor cross-drilling of the compressor section and saving time and expenseassociated with cross-drilling operations. As such, unitizing themanufacturing and assembly details, while integrating complexperformance-enhancing features using additive manufacturing techniques,lowers the overall production costs and manufacturing time.

FIG. 1 shows attritable engine 100 including compressor section 102,lubrication system 104, rotor 106, forward ball bearing assembly 108,rearward ball bearing assembly 110, ball bearings 112 a and 112 b, innerraces 114 a and 114 b, outer races 116 a and 116 b, retaining clips 118a and 118 b, lubrication channel inlet 120, lubrication distributionrail 122, lubrication channel 124, lubrication channel outlet 126, anddispersion cone 128.

Compressor section 102 houses lubrication system 104 and rotor 106,which is journaled in forward ball bearing assembly 108 and rearwardball bearing assembly 110. Forward ball bearing assembly 108 includesball bearing 112 a surrounded by inner race 114 a and outer race 116 aand retained in place by retaining clip 118 a. Similarly, rearward ballbearing assembly 110 includes ball bearing 112 b surrounded by innerrace 114 b and outer race 116 b and retained in place by retaining clip118 b.

Operationally, air enters the forward end of compressor section 102 andis compressed by compressor blades and vanes. Compressed air and fuelenter a combustor where the compressed air and fuel are mixed andignited. The resulting high-temperature gas from the combustor enters aturbine section and drives the rotation of turbine blades, which in turngenerates power by turning rotor 106 circumferentially about an axis ofrotation. Gas exits the engine out of the aft end of an exhaust section.

Lubrication system 104 provides lubricant to forward and rearward ballbearing assemblies 108 and 110 from a lubricant source such as, forexample, a fuel tank or an oil tank. Lubricant can be any fluid thatprovides cooling to bearings 112 a and 112 b such as, for example, fueland oil. Lubricant enters lubrication system 104 from a lubricant sourceat lubricant channel inlet 120 and is delivered to lubricationdistribution rail 122, which distributes lubricant to lubricationchannel 124. Lubrication distribution rail 122 can distribute lubricantto more than one lubrication channel 124. One or more of the lubricationchannels can have a curved shape along all, substantially all, or justpart of its length. Lubrication distribution rail 122 circumferentiallytravels around the engine casing and may travel all the way around theengine casing or only partially around the engine casing, distributinglubricant to multiple lubrication channels 124.

Lubricant exits lubrication system 104 at lubrication channel outlet 126and is dispersed in dispersion cone 128, which has a frustoconical shapeand is configured to diffuse the lubricant as the lubricant travelsthrough dispersion cone 128. Diffusion of the lubricant helps thelubricant form a fine mist. The lubricant exits dispersion cone 128 andis distributed on the exterior surface of outer races 116 a and 116 b.Dispersion cone 128 may also be referred to as a diffuser.

FIG. 2 is a cross-sectional view of a spray cone with an airfoildistribution array. FIG. 2 shows lubrication system 204 includinglubrication channel 224, lubrication channel outlet 226, dispersion cone228, and dispersion enhancements features 230. Lubrication system 204depicts one embodiment of lubrication channel 124, lubrication channeloutlet 126, and dispersion cone 128.

Lubricant exits lubrication channel 224 of lubrication system 204 atlubrication channel outlet 226 and is dispersed in dispersion cone 228,which has a frustoconical shape and is configured to diffuse thelubricant as the lubricant travels through dispersion cone 228.Dispersion enhancement features 230 increase the dispersion oratomization of the lubricant as the lubricant travels through dispersioncone 228 compared to a dispersion cone without any dispersionenhancement features.

Dispersion enhancement features 230 can have any geometry, size, orshape that increases the dispersion or atomization of the lubricant asthe lubricant travels through dispersion cone 228. In one embodiment, asdepicted in FIG. 2 , dispersion enhancement features 230 have an airfoilshape. In other embodiments, dispersion enhancement features 230 can bespars, ramps, indentations, and combinations thereof.

Lubrication systems 104 and 204 can be formed of stainless steel. Inother embodiments, lubrication systems 104 and 204 can be formed ofaluminum, titanium, copper, cobalt, iron, nickel, and alloys thereof.Lubrication system 104 is built integral and conformal with attritableengine 100 and can be manufactured using additive manufacturingtechniques such as laser powder bed fusion, electron beam melting, andglue binder jetting.

Lubrication systems 104 and 204 have dispersion cones configured to forma mist of lubricant. This mist evenly covers the exterior surface of theouter races, thereby efficiently cooling ball bearing assemblies duringoperation of the engine. Furthermore, these lubrication systems can beadditively manufactured, which simplifies the manufacturing process byobviating the need for cross-drilling of the compressor section andallows for the lubrication channels to be curved in whole or in part.Forgoing subtractive manufacturing techniques such as drilling saves thetime and expense associated with subtractive manufacturing operations.As such, unitizing the manufacturing and assembly details, whileintegrating complex performance-enhancing features using additivemanufacturing techniques, lowers overall production costs and enginemanufacturing time.

DISCUSSION OF POSSIBLE EMBODIMENTS

The following are non-exclusive descriptions of possible embodiments ofthe present invention.

A gas turbine engine with a lubrication system includes a ball bearingassembly and a rotor circumscribing a rotational axis and journaledwithin the ball bearing assembly. The gas turbine engine also includes alubrication system located radially outward from a rotational axis andradially outward and adjacent to the ball bearing assembly, whichincludes a lubrication channel having an inlet and an outlet and adispersion cone adjacent to the outlet of the lubrication channel.

The gas turbine engine of the preceding paragraph can optionallyinclude, additionally and/or alternatively, any one or more of thefollowing features, configurations and/or additional components:

The ball bearing assembly of the gas turbine engine includes an innerrace attached to the rotor, a ball bearing adjacent to and locatedradially outward of the inner race, an outer race adjacent to andlocated radially outward of the ball bearing, and a retaining clipadjacent to the outer race and configured to retain the ball bearingassembly in place.

The dispersion cone is adjacent to an exterior surface of the ballbearing assembly and configured to evenly coat the ball bearing assemblywith a lubricant.

The dispersion cone of the gas turbine engine includes a dispersionenhancement feature.

The dispersion enhancement feature is at least one airfoil shaped spar.

The dispersion enhancement feature is at least one of a spar, ramp,indentation, and combinations thereof.

The dispersion enhancement feature is configured to provide a mist toevenly coat the exterior surface of the ball bearing assembly with alubricant.

The dispersion cone has a frustoconical shape with a base that isadjacent to the ball bearing assembly and an apex that is adjacent tothe outlet of the lubrication channel.

The dispersion cone is oriented with the base of the frustoconical shapeadjacent to the ball bearing assembly and the apex of the frustoconicalshape adjacent to the outlet of the lubrication channel.

At least a portion of the length of the lubrication channel is curved.

The lubrication system is part of the housing of the compressor of thegas turbine engine.

A method of manufacturing a gas turbine engine with a lubrication systemincludes journaling a rotor within a ball bearing assembly andcircumscribing a rotational axis. The method also includes additivelymanufacturing a lubrication system located radially outward from arotational axis and radially outward and adjacent to the ball bearingassembly, which has a lubrication channel with an inlet and an outletand a dispersion cone adjacent to the outlet of the lubrication channel.

The method of the preceding paragraph can optionally include,additionally and/or alternatively, any one or more of the followingfeatures, configurations and/or additional components:

The method includes additively manufacturing the rotor and additivelymanufacturing the ball bearing assembly.

The dispersion cone is adjacent to an exterior surface of the ballbearing assembly and configured to evenly coat the ball bearing assemblywith a lubricant.

The dispersion cone includes a dispersion enhancement feature.

The dispersion enhancement feature is at least one airfoil shaped spar.

The dispersion enhancement feature is at least one of a spar, ramp,indentation, and combinations thereof.

The dispersion enhancement feature is configured to provide a mist toevenly coat the exterior surface of the ball bearing assembly with alubricant.

The dispersion cone has a frustoconical shape, oriented with the base ofthe frustoconical shape adjacent to the ball bearing assembly and theapex of the frustoconical shape adjacent to the outlet of thelubrication channel.

At least a portion of the length of the lubrication channel is curved.

The lubrication system is part of the housing of the compressor of thegas turbine engine.

While the invention has been described with reference to an exemplaryembodiment(s), it will be understood by those skilled in the art thatvarious changes may be made and equivalents may be substituted forelements thereof without departing from the scope of the invention. Inaddition, many modifications may be made to adapt a particular situationor material to the teachings of the invention without departing from theessential scope thereof. Therefore, it is intended that the inventionnot be limited to the particular embodiment(s) disclosed, but that theinvention will include all embodiments falling within the scope of theappended claims.

The invention claimed is:
 1. A gas turbine engine, comprising: a bearingassembly; a rotor rotatable about a rotational axis, the rotor journaledwithin the bearing assembly; and a lubrication system arranged radiallyoutward of and in fluid communication with the bearing assembly, thelubrication system comprising: a lubrication channel including an inletand an outlet; and a dispersion cone configured to receive lubricantfrom the outlet, the dispersion cone comprising a spar within aninterior of the dispersion cone, the spar formed integral with thedispersion cone, the spar configured to disperse the lubricant travelingthrough the dispersion cone, the spar extending between a leading edgeand a trailing edge, the leading edge having a blunt profile, and thetrailing edge having a sharp profile.
 2. The gas turbine engine of claim1, wherein the bearing assembly comprises a ball bearing assembly. 3.The gas turbine engine of claim 1, wherein the dispersion cone islocated at the outlet of the lubrication channel.
 4. The gas turbineengine of claim 1, wherein the spar comprises a foil.
 5. The gas turbineengine of claim 1, the bearing assembly further comprising: an innerrace mounted to the rotor; an outer race circumscribing the inner race;a bearing element radially between and engaged with the inner race andthe outer race; and a retaining clip adjacent to the outer race andconfigured to retain the bearing element in place.
 6. The gas turbineengine of claim 1, wherein the dispersion cone is adjacent to anexterior surface of the bearing assembly and configured to evenly coatthe bearing assembly with the lubricant.
 7. The gas turbine engine ofclaim 6, wherein the spar is configured to provide a mist to evenly coatthe exterior surface of the bearing assembly with the lubricant.
 8. Thegas turbine engine of claim 1, wherein the dispersion cone has afrustoconical shape with a base and an apex; the base is adjacent thebearing assembly; and the apex is adjacent the outlet of the lubricationchannel.
 9. The gas turbine engine of claim 1, wherein at least aportion of a length of the lubrication channel is curved.
 10. The gasturbine engine of claim 1, wherein the lubrication system is part of ahousing of a compressor of the gas turbine engine.
 11. A gas turbineengine, comprising: a bearing assembly; a rotor rotatable about arotational axis, the rotor journaled within the bearing assembly; and alubrication system arranged radially outward of and fluidly coupled withthe bearing assembly, the lubrication system comprising: a lubricationchannel including an inlet and an outlet; and a dispersion coneconfigured to receive lubricant from the outlet, the dispersion conecomprising an airfoil shaped spar within an interior of the dispersioncone, the airfoil shaped spar formed intergral with the dispersion cone,and the airfoil shaped spar configured to disperse the lubricanttraveling through the dispersion cone.